tag:blogger.com,1999:blog-57988456535209856042024-03-05T03:32:21.089-08:00Processors And StuffA blog to follow my endeavors into digital electronics, DIY microcomputers, retrocomputing and more! Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.comBlogger19125tag:blogger.com,1999:blog-5798845653520985604.post-56212210498624139152016-01-27T15:52:00.003-08:002016-01-27T15:52:59.133-08:00UpdateI've been absent on this for a bit, not slowing down progress, though.<br />
I've been through a lot of projects since last post, might do some posts about them.<br />
Projects include:<br />
> wire-wrapped z80 machine -working, very basically.<br />
> 8051 board, modifying a small trainer i bought.<br />
> Restoring a 1990's laptop for use as a serial terminal.<br />
> Designing an 8085 board with a million 82xx chips<br />
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I've gotten some new test gear, too. Most notably a 70's vintage Philips logic probe and pulser - some of the greatest tools I've ever owned.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKNYazRS672ehQ9ms9jfDHfdEz7M7d0zbVxhBstZgdolo2AA6WYvnlylQniiTW8nNImQ3eG680_pYkjUK-8lL9rNFB-0PiafsMMBTJRIGP_F1iaQRiIDuhymsRJypVSmTYgTE5TIV71Jk/s1600/WD-1511.JPG" imageanchor="1"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKNYazRS672ehQ9ms9jfDHfdEz7M7d0zbVxhBstZgdolo2AA6WYvnlylQniiTW8nNImQ3eG680_pYkjUK-8lL9rNFB-0PiafsMMBTJRIGP_F1iaQRiIDuhymsRJypVSmTYgTE5TIV71Jk/s400/WD-1511.JPG" width="400" /></a><br />
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This is the z80 computer I'm currently working on.<br />
Right now it features only dip switches as inputs, led's as outputs.<br />
additional features will include a 8250 uart, 8255 PIO, and more!<br />
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That's it for now!<br />
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Think I might have something cool to bring forth (get it? forth?) soon.<br />
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--ChristofferStoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-73155752018465318962015-06-09T14:16:00.000-07:002015-06-09T14:16:09.645-07:00I LIED! IT'S NOT ALL ABOUT COMPUTERS!! HERE COMES ANALOG SYNTHESIZERS! <span style="font-family: Courier New, Courier, monospace;">So yeah. Am doing modular synthesizers now. Still will do computers once in a while, but NOT NOW!</span><br />
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<span style="font-family: Courier New, Courier, monospace;">Here's my synth so far. All modules homemade. To the eurorack std.</span><br />
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<span style="font-family: Courier New, Courier, monospace;"><br /></span>Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-49019415054354834552015-04-12T17:35:00.004-07:002015-04-12T17:35:56.170-07:00Z8671: Tinybasic on a z8 processor<span style="font-family: Courier New, Courier, monospace;">When burrowing though a big box of unsorted IC's, like Scrooge McDuck though his money bin, i came across a chip I'd never seen or heard of before: Zilog Z8671 (BASIC/DBUG). Upon reading the "Zilog Z8-something" part i got hyped because i assumed it was a Z80 support chip, like the standard 6800 support chips are all called 6850, 6821, etc. and 8080 chips are called 8212 and so on.</span><div>
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<span style="font-family: Courier New, Courier, monospace;">I was very very wrong, but that didn't diminish the hype. The Z8671 is a chip in Zilog's Z8 microcontroller series: one that has an internal mask ROM with tinybasic! </span></div>
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<span style="font-family: Courier New, Courier, monospace;">Later I found some information leading to a Steve Ciarcia's Circuit Cellar (a series in BYTE magazine) that spoke about this tiny MicroMint z8671 board (Micromint is still around, it seems). -Alas it was much later that i found an actual schematic</span><span style="font-family: 'Courier New', Courier, monospace;"> for the system, and was able to start the work.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">A similar circuit is shown in the Z8 handbook/application book, but it had certain oddities: it was meant for the z8671, but it still incorporated a 27128 EPROM, with no explanation as to what was to be put in it. (Also, at that time, i didn't have access to an EPROM-programmer, which i do now, <b>and now consider the greatest and most vital tool in DIY computer electronics at all: EPROM PROGRAMMER: backup-ing vintage ROM's, writing your own rom's for systems; even setting EPROMs up as programmable logic!</b></span></div>
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<span style="font-family: Courier New, Courier, monospace;">Anyway, decided I wanted to do the machine with wirewrap: had all the ic sockets and a nice eurocard protoboard to build it on.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">-Had little to no wirewrap wire, though. It arrives tomorrow, updates will follow, but so far:</span></div>
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<span style="font-family: Courier New, Courier, monospace;">The Toshiba RAM is a placeholder IC, since I used two loose SIP wrap lists and needed to hold them in place: the same with the Z80 processor: I keep a box of dead or useless IC's for this kind of purpose, also to mock-up component layouts.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">My only problem is: I have only one of these IC's. So if the z8671 I have turns out to be a goner, I'm screwed.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">That's it</span></div>
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Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com1tag:blogger.com,1999:blog-5798845653520985604.post-38230020761239615862015-01-01T19:00:00.002-08:002015-01-01T19:01:49.529-08:00Progress! Lack of progress! TESTGEAR!<span style="font-family: Courier New, Courier, monospace;">So It's been a while. Been doing some RF projects for ham radio the last months, and been a bit out of the loop with the microcomputers. Until my interest was sparked by a piece of test gear:</span><br />
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<span style="font-family: Courier New, Courier, monospace;">I got a logic analyzer! Thurlby (Tti) LA4800 48CH. logic analyzer!</span><br />
<span style="font-family: Courier New, Courier, monospace;">It was fairly cheap, even though it lacks the probes. The thurlby analyzers uses these pods with IDC connectors, which basically just contains some input protection and some buffers. It says in the manual that you really just COULD connect wires directly to the input connectors, but there is NO input protection what so ever. they feed right into some standard 7400-logic buffers and some SIP resistors for pullup(down?), so if you feed it a smidgen more than 5V, you burn those (at best). Probes are coming along nicely, probably done by tomorrow (might make an update on them). </span><br />
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<span style="font-family: Courier New, Courier, monospace;">The interface is really nice, it's intuitive, took me ½ an hour without manual to get a basic understanding of it. It does both timing and state analysis, and also has an external clock input.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">It comes with some nice sets of default settings; 8 bit computer</span><br />
<span style="font-family: Courier New, Courier, monospace;">being one of the better. Pictured is some banks of test data it had.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">The hardware seems dated 1992- design is probably late 80's early 90's. </span><br />
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<span style="font-family: Courier New, Courier, monospace;">The main board is almost entirely trough-hole, the only smd stuff being the LCD drivers on the module. </span><br />
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<span style="font-family: Courier New, Courier, monospace;">Most chips are 7400-series, with some nice big RAM for the datalogging. processor(s), yes, it has two, each associated with an eprom and some more ram; I'm suspecting one set is purely for the RS432 communications. Anyway, processors are Hitachi HD6303 processor.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">The display has wonderful contrast, even contrast and brightness setting. </span><br />
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<span style="font-family: Courier New, Courier, monospace;">Truly a very neat bit of gear.</span><br />
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<span style="font-family: Courier New, Courier, monospace;"><br /></span>Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-74745748881130871672014-10-15T17:57:00.000-07:002014-10-15T17:57:37.067-07:00New project!<span style="font-family: Courier New, Courier, monospace;">So, the z80 system 2 project being on hold until i get a functioning EPROM burner, I've moved forward on another project: The COSMAC ELF.</span><br />
<span style="font-family: Courier New, Courier, monospace;">Though I've made some hardware mods, it is functionally equivalent of the original ELF. My mods include: </span><br />
<span style="font-family: Courier New, Courier, monospace;"><br /></span>
<span style="font-family: Courier New, Courier, monospace;"> - Changing the HEX display to binary LED's; way cheaper.</span><br />
<span style="font-family: 'Courier New', Courier, monospace;">This mod was actually suggested in the original article.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">- Changed the two 4 bit 2101 RAM's for eight 1 bit 2102 ones.</span><br />
<span style="font-family: 'Courier New', Courier, monospace;">I had them lying around and besides the "width" they're very similar. Furthermore, they're 1977 vintage - adds something to the design.</span><br />
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<span style="font-family: 'Courier New', Courier, monospace;"> - Sprung for another layout, not wirewrap </span><br />
<span style="font-family: 'Courier New', Courier, monospace;">Once again, I'm out of wrap wire, and I kinda wanted it to have more of a Altair 8800 / MIPS 8080 kinda look.</span><br />
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<span style="font-family: 'Courier New', Courier, monospace;">Here it is:</span><br />
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<span style="font-family: Courier New, Courier, monospace;">The 8 chips with dual round indents are the RAM.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">I have redrawn the schematic into a more reader friendly form than the original, spreading it over 6 pages:</span></div>
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<span style="font-family: Courier New, Courier, monospace;">1) CPU and clock</span></div>
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<span style="font-family: Courier New, Courier, monospace;">2A) Original RAM</span></div>
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<span style="font-family: Courier New, Courier, monospace;">2B) My RAM</span></div>
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<span style="font-family: Courier New, Courier, monospace;">3) I/O logic</span></div>
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<span style="font-family: Courier New, Courier, monospace;">4) Display</span></div>
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<span style="font-family: Courier New, Courier, monospace;">5) Input</span></div>
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<span style="font-family: Courier New, Courier, monospace;">6) CPU control</span></div>
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<span style="font-family: Courier New, Courier, monospace;">Makes it much easier to debug and alter.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">Anyway, so far, I've wired the processor control and power.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">Buses are to come.</span></div>
<span style="font-family: 'Courier New', Courier, monospace;"><br /></span>Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-54645957863978473932014-09-30T09:20:00.000-07:002014-09-30T09:20:36.249-07:00Diode matrix ROM for the Z80, or: How a silly, not-so optimized idea became a main design choice. <span style="font-family: Courier New, Courier, monospace;">Ok, so the phase one hardware design for the z80 system B is almost done. Even started on expanding, but I would like to have it running first. But alas: having no EPROM's, and no burner for them, i had to think of something for a complete hardware test. So i decided to code three small program snips into a diode matrix ROM for it.</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicWLINbNjh6QQpXfWGLhFXtvpJ8FOZ12ZYOXfRyzyBvgMPZj-l1rkUjXA3HRY-mvOuzLNJfMUAnrIXuRVtcC-ospW48-XTbiW2S_Hc0A7Wnm0OmcKwmZy6AbzSZ6EUMFPa8-jIlSDLVL4/s1600/IMG_0251.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicWLINbNjh6QQpXfWGLhFXtvpJ8FOZ12ZYOXfRyzyBvgMPZj-l1rkUjXA3HRY-mvOuzLNJfMUAnrIXuRVtcC-ospW48-XTbiW2S_Hc0A7Wnm0OmcKwmZy6AbzSZ6EUMFPa8-jIlSDLVL4/s1600/IMG_0251.JPG" height="480" width="640" /></a></div>
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<span style="font-family: Courier New, Courier, monospace;">What a beauty! I've expanded the design (see last post) for 32 bytes, using 2 74154 4-16 decoders, and then feeding the lower 4 addresses into those. the next two addresses are fed to a 2-4 decoder, whose 1 and 2 output enables either chip 1 or 2.</span><br />
<span style="font-family: Courier New, Courier, monospace;">The design of the diode matrix itself was a bit tricky. Most designs needs either multiple boards, or 3d arrays of wires, but eventually, i landed on having each trace (32 of them) for each line run all the length of the left half of the board. then, soldering tin/copper wire across the top of the board, and connecting those to the data lines, with pull ups. the result is rather neat, in its own right.<br />The bytes are read upwards, meaning that A0 is the lowest row, and so on. A diode indicates a 0, while a missing diode is 1. This is stupid, in terms of saving diodes, since 00 is used more often than FF, but yeah. Still needs some bytes, though, i ran out of diodes.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">It should be able to mimic a 2716, or any device, really. I may need a tri-state buffer on DATA bus, and have the gate tied to /CS, to keep the bus floating from the pull ups. We'll see.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">Once again, the sample programs are some counters and stuff i found on Donn Stewart's z80 page. I still haven't gotten around programming yet.</span>Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-22153316599941925922014-09-10T03:05:00.004-07:002014-09-10T03:14:49.127-07:00A ROM substitute / development tool<span style="font-family: Courier New, Courier, monospace;">So, I have run into the problem of needed programmed devices for my computer projects. A CPU cannot (mostly) start proper operation without some lines of code. Thus raising the problem: how to test your system without a ROM? Well, i was reading up on the 74154 IC. It's a 4 to 16 line decoder. So i got the idea, of making a diode prom with it, using four address lines, eight data lines, and dip switches with diodes. The solution looks like this:</span><br />
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<span style="font-family: Courier New, Courier, monospace;">An address is entered on the An to An+3 (you can use whichever four addresses the system reads first, it varies with processor) and then, the two chip select and output enable (they're not called that on the 154, i've made the pinout compatible with the 2716), connected as well as the data lines, and then on the 16 x 8 dip switches, you can enter the programs or routines you want. 16 bytes seems infinitely small, but plenty of room for some test, and a HLT or so. a counter maybe. The 74ls240 is just an 8 bit inverting tru state buffer. You might need to connect the /G lines which disables output to /READ. </span><br />
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<span style="font-family: Courier New, Courier, monospace;">Note: This is kinda WIP, i haven't tested or even built this yet, so I'm just throwing it out here for the interested.</span></div>
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Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-84818503840940762062014-09-09T13:08:00.001-07:002014-09-09T13:08:17.947-07:00EUREKA! - HARDWARE HELLO WORLD!<span style="font-family: Courier New, Courier, monospace;">And thus, without any bugs (so far), the V.1 hardware of the Z80 SYSTEM B is complete.</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLFNIzBOsJbmUGHFQCO3nEBkXd-CFq8err-wjEUok88LxlGRpeHV9kYHDWhhbbVmG79IqIqhWL3Xxr63FwPJQ5LXKPqB168sKnS4ysM_9Ie166EXt_GezBrtKqfypzT01nNfTGeAbAEqA/s1600/IMG_0249.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLFNIzBOsJbmUGHFQCO3nEBkXd-CFq8err-wjEUok88LxlGRpeHV9kYHDWhhbbVmG79IqIqhWL3Xxr63FwPJQ5LXKPqB168sKnS4ysM_9Ie166EXt_GezBrtKqfypzT01nNfTGeAbAEqA/s1600/IMG_0249.JPG" height="480" width="640" /></a></div>
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<span style="font-family: Courier New, Courier, monospace;">Ain't that pretty? I have no idea what it's doing, though, it's clearly doing something, and at one point, it read data from port 0, and as you see, it displays something on ports as well. There is no system ROM, so I'm guessing it must be random data stored in the RAM... Anyway the hardware is behaving as expected, so all good so far. Now; for the ROM..</span><br />
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<span style="font-family: Courier New, Courier, monospace;">And as a side note: step 2 hardware includes qwerty keyboard and LCD from a early 80's electronic typewriter.</span>Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-62738607843944832152014-09-06T09:51:00.000-07:002014-09-06T09:51:16.023-07:00Z80 System B update<span style="font-family: Courier New, Courier, monospace;">So, the only thing lacking hardwarewise on the Z80 system I'm building, is the I/O. Once more, I was very inspired by Donn Stewarts <a href="http://cpuville.com/Z80.htm">z80 project</a> in my port control logic, though I've made a connector for an external "terminal".</span><br />
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<span style="font-family: Courier New, Courier, monospace;">As you see, the "terminal" is really just two ports of LEDS as output and slide switches as input. The cable goes to a 40 pin DIL ribbon connector and socket, to port select and latching, etc.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">This is the interface board, using the 74LS139 as address decoder/port selector, and 74LS244 for input buffers, 74LS373 for display latches. Still needs wiring.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">And Wouldn't you know: The board cracked! when i was scoring the rectangular cutouts for the switches! The pcb material were.. not good; had a consistency as wet crackers, and flaked like slate, meaning when it cracked (the entire bottom right quarter) it sliced the palm of my hand right up! but i was able to fix it (the board, that is; the hand takes care of itself) by means of screwing on a little piece of pcb on the underside, and solder some of the traces back. Holds quite well. </span></div>
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<span style="font-family: Courier New, Courier, monospace;"><br /></span>Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-84463800322994034652014-09-05T10:57:00.001-07:002014-09-05T10:57:28.031-07:00Historic PROM burner: The DATAIO model IX<span style="font-family: Courier New, Courier, monospace;">So, i bought this some time ago, a really interesting artifact of computer/digital electronics history.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">It is, as far as my research go, nothing less than the worlds first microprocessor controlled PROM burner!</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPZ98gIcQ_NmrV5cWsh_dnHb-8EQj2JZt-MQCGYqGkUZ_X8HQeglToPxtsJ0iJ5aYsI3naFVXShKL3QVAq-3mz76yWahXCYcePulHWCUEvmzko-vKiTUkVWqn6hK7E_wJd4oWA6mz-OYA/s1600/IMG_0025.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPZ98gIcQ_NmrV5cWsh_dnHb-8EQj2JZt-MQCGYqGkUZ_X8HQeglToPxtsJ0iJ5aYsI3naFVXShKL3QVAq-3mz76yWahXCYcePulHWCUEvmzko-vKiTUkVWqn6hK7E_wJd4oWA6mz-OYA/s1600/IMG_0025.JPG" height="480" width="640" /></a></div>
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<span style="font-family: Courier New, Courier, monospace;">Yup, that's it. Pretty good condition, except for one missing button cover on the EDIT. It can check memory, copy it, browse through addresses, and many other functions. It has a parallel Dsub25 connector on the back, for "remote operation" - whether that means having "slave" programmers for multiple chips, or the unit being able to be controlled by other systems. I haven't found ANY documentation on this; no manual, nothing. the only reference to it is a note on DATA IO's website, under a <a href="http://www.dataio.com/company/aboutdataio/40thanniversary/1970s">company history timeline</a>.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">On the same timeline, they state that model 19 is the first microprocessor controlled burner (with MC6800) - That is wrong, since this model is earlier, and IS controlled by a 6800, making THIS the first. Though, whether it's the worlds first or the company's, I really haven't the foggiest.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">THE GUTS</span><br />
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The case is in fiberglass, and split color blue/white, and is mounted on a 8 mm aluminum bottom plate - really adds some weight.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9-Y7mb9qogahOkLN4rZNB70L5-SzIPdBBwoDcaqt2X1scl8ktXS2iqQwvXBwkwBzN0CoONLWx5G42D8Sfn5qUshZa3fwVeeSXFmtL8SKBNcfNwnDOVKTmBLKnMrUTB1TusQeOepsO_pA/s1600/IMG_0021.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9-Y7mb9qogahOkLN4rZNB70L5-SzIPdBBwoDcaqt2X1scl8ktXS2iqQwvXBwkwBzN0CoONLWx5G42D8Sfn5qUshZa3fwVeeSXFmtL8SKBNcfNwnDOVKTmBLKnMrUTB1TusQeOepsO_pA/s1600/IMG_0021.JPG" height="640" width="480" /></a></div>
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<span style="font-family: Courier New, Courier, monospace;">The computer part, which is what we want, is mounted in a little rack system, with a backplane bus of chained card-edge connectors on ribbon cable. There are 4 boards, with those lovely "ears" for releasing them from the rack.</span></div>
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<span style="font-family: 'Courier New', Courier, monospace;">************************</span><span style="font-family: Courier New, Courier, monospace;">THE PROCESSOR BOARD</span><span style="font-family: 'Courier New', Courier, monospace;">************************</span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0htGrPZmUWVY5kVIJUg2lL8mIfdBg_GlsL5jys0zuQYR4vQgs9SOrQ4h8NRDlzNQ5EU7tWJ_1h59-EbOGMcpP0sbzXGlGcqgMCd_WgHVvDuqD60M0eumu_QcXXIU0bIsxoTD89FLFC9M/s1600/Main+Processor+board.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0htGrPZmUWVY5kVIJUg2lL8mIfdBg_GlsL5jys0zuQYR4vQgs9SOrQ4h8NRDlzNQ5EU7tWJ_1h59-EbOGMcpP0sbzXGlGcqgMCd_WgHVvDuqD60M0eumu_QcXXIU0bIsxoTD89FLFC9M/s1600/Main+Processor+board.JPG" height="480" width="640" /></a></div>
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<span style="font-family: Courier New, Courier, monospace;">If that ain't retro, I don't know what is! The memory is shared over 4 chips - 2x 2708 1K EPROMs, the white ceramic with gold windowframe/legs! i had to cover them, i were afraid the flash of the camera could damage the memory, so the windows are covered with masking tape. The plastic DIP24 with the sticker must be system ROM, and the MC6810 is the typical RAM to go with the MC6800. This RAM, is probably system RAM, there must be a reason why the RAM is split on two boards - more on that later. The shiny can is the MC6871A - an oscillator / two phase clock for the 6800. Not much else, a little logic and some jumpers. Notice how the address range of the memory is labeled in the silk screen: C600-C7FF and so on. That's neat!</span></div>
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<span style="font-family: Courier New, Courier, monospace;">************************MEMORY BOARD</span><span style="font-family: 'Courier New', Courier, monospace;">************************</span><span style="font-family: 'Courier New', Courier, monospace;"> </span></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBxp2ySkV8EKAmETIHcNCytYtkP7TEy1gZmdLdS9QTVRv3ehvPURnqmt3bYEv7depO03odndyLJRyqDpHbMpPrxg5v4IGDnUIj7kwVvh9OItzjUHt97PzzeIlNSn_qCaM1LIb99xq_UYE/s1600/RAM+board.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBxp2ySkV8EKAmETIHcNCytYtkP7TEy1gZmdLdS9QTVRv3ehvPURnqmt3bYEv7depO03odndyLJRyqDpHbMpPrxg5v4IGDnUIj7kwVvh9OItzjUHt97PzzeIlNSn_qCaM1LIb99xq_UYE/s1600/RAM+board.JPG" height="480" width="640" /></a></div>
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<span style="font-family: Courier New, Courier, monospace;">This is the RAM board. Little more than 2 <a href="http://www.datasheetarchive.com/Am9131ADC-datasheet.html">AM9131ADC</a> 1024x4 SRAM chips - yes, Advanced Micro Devices, AMD. Apparently, This can be expanded, by the two empty sockets. The RAM IC's is in the purple/grey/gold packages - same as the 6800 itself. I believe this RAM is for holding the PROM code in memory.</span><br />
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<span style="font-family: 'Courier New', Courier, monospace; text-align: center;">************************ I/O </span><span style="font-family: 'Courier New', Courier, monospace; text-align: center;">************************</span><br />
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<span style="font-family: 'Courier New', Courier, monospace; text-align: center;">The I/O is again, as far as i can tell, very much standard 6800 peripheral stuff:</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRdNp9rGnzCrfGbYj84EMCJT9bHbMaYaLBrZeXTlzrJT36CxJ4lOZIZuMP5AhkPNgQ3Em4xxWthz-do9TgUy4UflsF2uIiUe7_4NP_eBadhGIbjuQK54RBW7N-fKxcQNQR95a1AOe4LWc/s1600/IO+board.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRdNp9rGnzCrfGbYj84EMCJT9bHbMaYaLBrZeXTlzrJT36CxJ4lOZIZuMP5AhkPNgQ3Em4xxWthz-do9TgUy4UflsF2uIiUe7_4NP_eBadhGIbjuQK54RBW7N-fKxcQNQR95a1AOe4LWc/s1600/IO+board.JPG" height="480" width="640" /></a></div>
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<span style="font-family: 'Courier New', Courier, monospace; text-align: center;">The 24 pin DIP package is the MC6850 ACIA Asynchronous Communications Interface Adapter, acting as an UART. The 40 pin package is the MC6821 peripherals adapter, driving, by the looks of the bus, the header connector top left, which goes to the front panel. The smaller second card edge connector (right) goes to the DSUB 25 connector. And a baud rate switch for the ACIA - what would happen if you activated more than one?</span><br />
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<span style="font-family: 'Courier New', Courier, monospace; text-align: center;">The main programming cards and IC sockets are connected directly to the main system bus, and consists of a set of two chip specific cards: A digital, dealing with timing and such, and an analog, setting voltages. I have yet to find any references as to what PROM my system is set up for, but changing chip for this model of burner must be quite a challenge. The analog board also needed calibration.</span><br />
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<span style="font-family: 'Courier New', Courier, monospace; text-align: center;">There's much more, so I'll probably do a follow up, but this is a brief description (ha. BRIEF) of the microprocessor/computer based parts. </span><br />
<br />Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-55515503437234040592014-09-05T09:31:00.000-07:002014-09-05T09:31:08.557-07:00Burning EPROMS the stupid way<span style="font-family: Courier New, Courier, monospace;">So I'm reaching a point where I'll need to work on my ROM. Step one involves little more than some tests and the ability to punch in programs via the input ports. The system ROM is a 2716 EPROM, because i think it's neat because it's pin compatible with my RAM, so i can reuse the board later on. I found my EPROM burner, and wept. I completely forgot, it works, but it is.. not my fines piece of DIY gear. ADDR and DATA is set with a sharp pencil and DIP-switches, and binary data readout on the little floating board.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">The only thing even remotely nice about it is the genuine 3M TEXTOOL socket, (not installed on the pic).</span><br />
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<span style="font-family: Courier New, Courier, monospace;">Since I'm only at 60-100 bytes at the moment, this abomination is adequate, but i really need to make a more optimized one. With HEX rotary switches, 7seg readouts, and "jump to next address" button.</span><br />
<br />Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-31444440737689662752014-09-04T06:10:00.004-07:002014-09-04T06:12:42.858-07:00Z80 computer update<span style="font-family: Courier New, Courier, monospace;">It ALMOST lives. I'm currently working on the IO interface, which is just some latches and buffer logic with two ports of 8 LEDS and 8 switches. This "terminal" is connected via rainbow ribbon to a socket on the IO board:</span><br />
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<span style="font-family: Courier New, Courier, monospace;">The board is yet to be wired, which will be done in the style of the memory board.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">The system as of writing looks like this:</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeS5asAJiUrVSiYq0VPTDYbxe-l14IoN6wAYTdUsNWTDkEZ_nCayJYqedj3vsXqDx8fa5MkAYxidYZTBks9I4LhKtD2PcdoYOByuTqwdt78ieFrickUbdsu2w8hGc8545LOhztgKfCQc0/s1600/IMG_0238.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeS5asAJiUrVSiYq0VPTDYbxe-l14IoN6wAYTdUsNWTDkEZ_nCayJYqedj3vsXqDx8fa5MkAYxidYZTBks9I4LhKtD2PcdoYOByuTqwdt78ieFrickUbdsu2w8hGc8545LOhztgKfCQc0/s1600/IMG_0238.JPG" height="480" width="640" /></a></div>
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<span style="font-family: Courier New, Courier, monospace;">The card labeled "memory card" is the memory card, and likewise with the others. You probably guessed that, though. I haven't made/bought the PSU yet, so it is powered by a variable psu, adjusted with a DMM. The ribbon is supposed to go to an angled front plate.</span>Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-25628410664110576382014-08-30T19:32:00.002-07:002014-08-30T19:36:38.724-07:00Memory circuit wired<span style="font-family: Courier New, Courier, monospace;">This is the memory card for my Z80 system. It contains a single 8x2k SRAM, the 6116-2, one of my favorite SRAM's, because its name is a palindrome. A 2716 EPROM of same size (and pin compatible, by the way) is used as system ROM. Address decoding for chip select with a 74139. Memory decoding entirely after <a href="http://cpuville.com/Z80.htm">Donn Stewart's Z80 computer</a>. A more refined point-to-point wiring technique than with the <a href="http://processorstuff.blogspot.dk/2014/08/the-indicator-card-done.html">indicator card</a>, and i think it's really neat! Maybe even more so than wire-wrap. </span><br />
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<span style="font-family: Courier New, Courier, monospace;">Using the same wire to make little ties for the wire bundles. </span></div>
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<span style="font-family: Courier New, Courier, monospace;">For this method, start by wiring power, then control logic, and THEN DATA and ADDRESS buses, as you see, they are the ones who takes up space. Make sure that the wires are approximately the right length to be routed, and then after soldering of a bundle, begin "neating" with wire ties, either free floating or though holes in the PCB. excess length can be huddled up at one end (here, at the connector). </span></div>
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Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-53055021221146972892014-08-30T09:07:00.002-07:002014-08-30T09:07:51.896-07:00Some tips for starting a microcomputer project<br />
<span style="font-family: Courier New, Courier, monospace;">When setting out to build a microcomputer, especially for a first computer project, there are a lot of unknowns. There's a lot of project schematics out there, some more advanced than others, and a lot of them seems like just a schematic with no notes attached. </span><br />
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<span style="font-family: Courier New, Courier, monospace;">Since none of my projects are in any state near "complete", this is simply some of the points I've noticed so far. </span><br />
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<span style="font-family: Courier New, Courier, monospace;"> <b>- Decide on a processor </b></span><br />
<span style="font-family: Courier New, Courier, monospace;">You'll probably need to base your computer around a microprocessor. Wiring your own is an interesting idea, but leagues ahead of most computer hobbyists (assuming they still exist). </span><br />
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<span style="font-family: Courier New, Courier, monospace;">I'd recommend an 8-bit processor, since that's basically all you need, and there's no need adding to the complexity.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">Popular ones include the <b>ZILOG</b> <b>Z80</b>, my favorite. It is fairly easy to interface to other hardware, only needs a single phase clock, and the instruction set (for programming) seems rather intuitive to me. The <b>MOS</b> <b>6502</b>, made famous by the Commodore and Acorn computers is also pretty easy, and has found many applications in DIY computers in the past, though it does need a two phase clock, and the instruction set is a little more confusing ( i MAY be biased on this, if you started learning 6502 assembly, you'd probably feel the same way about the z80's).</span><br />
<span style="font-family: Courier New, Courier, monospace;">The <b>RCA COSMAC 1802</b> , notably used in the COSMAC ELF DIY computer, is very easy to interface, and RUNS WITHOUT A ROM, which eliminates the need for a device programmer, is very rare, and although classic and awesome, i really wouldn't recommend it for first time builders. The COSMAC ELF articles talk about a video interface on a chip, which is even harder to find. Don't bother, unless you REALLY want to.</span><br />
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<span style="font-family: Courier New, Courier, monospace;"><b> - Learning to program </b></span><br />
<span style="font-family: Courier New, Courier, monospace;">You'll need to be able to program your ROM, so you'll need to learn %PROCESSORNAME% assembly. So explained in BASIC:</span><br />
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<span style="font-family: Courier New, Courier, monospace;">10 you build a microcomputer to learn assembly, </span><br />
<span style="font-family: Courier New, Courier, monospace;">20 for which you need a microcomputer </span><br />
<span style="font-family: Courier New, Courier, monospace;">30 goto 10</span><br />
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<span style="font-family: Courier New, Courier, monospace;">See the problem? Yeah, you NEED an actual computer to learn to program (or an emulator, but that's cheating).</span><br />
<span style="font-family: Courier New, Courier, monospace;">You can get decent priced micro's still, use Wikipedia to find which mico's uses your processor. I've learned z80 assembler on a SINCLAIR ZX spectrum +2, which i found at a flea market.</span><br />
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<span style="font-family: Courier New, Courier, monospace;"> - <b>READ</b></span><br />
<span style="font-family: Courier New, Courier, monospace;">You need to find literature on system architecture. many books on this matter were published in the late 70's and the 80's. A lot of electronics can be learned by "monkey see monkey do" but understanding memory interfacing, I/O mapping (and some logic) will help you immensely.</span><br />
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<span style="font-family: Courier New, Courier, monospace;"><br /></span>Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-31583558807386543412014-08-29T06:10:00.000-07:002014-08-30T19:36:33.204-07:00Something else entirely<span style="font-family: Courier New, Courier, monospace;">This is NOT Z80 stuff! This is an artifact of early computing, something i found at a flea market for next to free:</span><br />
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<span style="font-family: Courier New, Courier, monospace;">This is a program! It may be hard to recognize, but this is a plugboard from an IBM tabulating machine. You actually connect the processor structure to do different stuff, no microinstructions! - I've yet to understand completely how this works, but nevertheless, this is almost a work of art! It is not made by IBM, but a company called MAC PANEL in Belgium. There was a label on it stating that it is from 1970, so even at that time, it would've been obsolete, these were popular in the late 40's to the 60's. Presumably for the <a href="http://en.wikipedia.org/wiki/IBM_421">IBM 421 tabulating machine</a>. The little grey plastic boxes are IBM branded hubs, interconnecting up to 3 of the plugs, which by the way, are 4mm banana plugs, though longer and "pointy". The program seems intact, no wires looks to have been tampered with (there's no dust on the edge of holes where plugs has been seated), so perhaps it's still executable!</span></div>
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<span style="font-family: Courier New, Courier, monospace;">Definitely a keeper.</span></div>
Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com1tag:blogger.com,1999:blog-5798845653520985604.post-68512276372193684172014-08-29T05:51:00.000-07:002014-08-30T19:35:47.157-07:00The indicator card done<span style="font-family: Courier New, Courier, monospace;">The indicator card made, with a different construction technique, since i wanted to exercise different prototyping methods for digital hardware. Okay, okay; I ran out of wire wrap wire.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">Thiss is 26 AWG wire, thicker than W-W. wire, but not much. Still so thin the insulation goes through the standard PCB holes. gives a good deal of strain relief, and allows for use as wire binders.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">Not much more to tell about this:</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPRI16je6LTUtDJxWbjXHHmgJ0wXfrH1m8I4KBUPVyGw3pJFjU04UxQ0EIsg1DDfEMgK8t1uDMXg40fqXqmADzlFFXPk8UhVNtEvHnMX66amhlIGRV87gLwqK55OEDporNIrBRSmNMTiA/s1600/2014-08-29+13.28.31.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPRI16je6LTUtDJxWbjXHHmgJ0wXfrH1m8I4KBUPVyGw3pJFjU04UxQ0EIsg1DDfEMgK8t1uDMXg40fqXqmADzlFFXPk8UhVNtEvHnMX66amhlIGRV87gLwqK55OEDporNIrBRSmNMTiA/s1600/2014-08-29+13.28.31.jpg" height="480" width="640" /></a></div>
<span style="font-family: Courier New, Courier, monospace;"> </span>Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-59688223316957649142014-08-29T05:40:00.001-07:002014-08-30T19:35:14.522-07:00The processor card<span style="font-family: Courier New, Courier, monospace;">The processor card is basically just a z80 with buffered buses and some functions. A clean reset circuit, and two clocks are on board as well. A manual step clock, and a slow clock ( a couple of Hz). This board, the clock and reset in particular, is inspired by <a href="http://cpuville.com/Z80.htm">CPUville's homebrew z80 project</a>. This also served as the inspiration for this project. </span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfy0E84DTvY4iwcmOS9VFIC4-mHv5ehe0ZYNzK-u_-tOEnAYJesUzsgYUpY7EKFqjgSl8_jIKZvhcaCniaTj4xh8Wdnw64R5jNZZefk-8yZTCaCkrV9NDdltLr7mxSgzHb4f-lcKG8cXk/s1600/2014-08-29+13.28.11.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfy0E84DTvY4iwcmOS9VFIC4-mHv5ehe0ZYNzK-u_-tOEnAYJesUzsgYUpY7EKFqjgSl8_jIKZvhcaCniaTj4xh8Wdnw64R5jNZZefk-8yZTCaCkrV9NDdltLr7mxSgzHb4f-lcKG8cXk/s1600/2014-08-29+13.28.11.jpg" height="480" width="640" /></a></div>
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<span style="font-family: Courier New, Courier, monospace;">This is the card. The red % button is the reset, and the toggle switch is the manual clock. the header matrix to the left of the processor is to select the clock via jumper, so you don't accidentally switch on two clocks at the same time. </span></div>
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<span style="font-family: Courier New, Courier, monospace;">Wire color code: RED: When it was closest. BLUE: When that was closest. Power is mainly routed on the solder side.</span></div>
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Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-67558700687485852014-08-29T05:23:00.001-07:002014-08-30T19:34:50.375-07:00Computer base and indicator card!<span style="font-family: Courier New, Courier, monospace;">OK, so these come pretty close one after another, since i'm actually past these steps, but behind on making a blog about it.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">Well, the base is made, as mentioned from wood, and the Indicator card is made.</span><br />
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<span style="font-family: Courier New, Courier, monospace;">Well this is the indicator /bus display card. It is nothing fancy, just a binary readout of the entire bus. Upper row are DATA (7-0 in reading order), the two rows are ADDRESS(15-0), and the lower six are: Reset, Clock, Memrq, IOrq, RD and WR.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">the four chips, 74LS241, is simply set up as noninverting buffers, which has some problems, since most of the control signals are active low. Good thing that won't confuse me when this machine doesn't do a thing!</span></div>
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<span style="font-family: Courier New, Courier, monospace;">Here be the base of the computer, the two cards installed. The dip socket on the bus card is to access the data bus, since i got the idea of wanting a little plug with pull-down resistors, to put the processor into free-run mode (just counting addresses, executing NOP's). Room is made for binary I/O, PSU, later: QWERTY keyboard, floppy drive, hard drive. </span></div>
Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0tag:blogger.com,1999:blog-5798845653520985604.post-62332836123749035092014-08-29T05:12:00.001-07:002014-08-30T19:34:44.276-07:00Z80 microcomputer (SYSTEM B)<span style="font-weight: normal;"><span style="font-family: 'Courier New', Courier, monospace;">This is the progress on my Z80 computer project! I've recently received</span><span style="font-family: 'Courier New', Courier, monospace;"> the needed components, and has begun construction.</span></span><br />
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<span style="font-family: Courier New, Courier, monospace;">The idea is, to make a eurocard (that's a PCB standard size) and backplane based microcomputer, which can be operated as simply as possible, but that also will allow for infinite expansions. </span></div>
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<span style="font-family: Courier New, Courier, monospace;">Phase 1 consists on little more than a buffered CPU card with clock, and a bus display card, showing the logic level of the address and data bus as well as some control bus signals.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">The "enclosure" is made of wood, to give that 70's homebrew feel, and the plan is not to use any component that didn't exist in the early to mid-80's.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">Above can be seen the first card to be plugged into the backplane. The connectors are DIN 41617 connectors, because i like how the pins match up with regular stripboard. The card pcb's is IC-island types, FR4 material. The 4 20-pin packages are simply buffers for various busses.</span></div>
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<span style="font-family: Courier New, Courier, monospace;">I use a mix of prototyping techniques, here it's wire-wrap, though i use standard 0.1-inch header pins as wrap posts. This has two major advantages, 1) The card becomes very low-profile, with the height being about 1,5 cm instead of the almost 4 with ordinary wrap sockets. 2) each socket costs a fraction of a wire-wrap one. The connection might not be as good, though. I've yet to experience problems with that. </span></div>
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Stoff0rhttp://www.blogger.com/profile/05909557194567316462noreply@blogger.com0